Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C1/00—Magnetic separation
  • B03C1/02—Magnetic separation acting directly on the substance being separated
  • B03C1/28—Magnetic plugs and dipsticks
  • B03C1/286—Magnetic plugs and dipsticks disposed at the inner circumference of a recipient, e.g. magnetic drain bolt
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C1/00—Magnetic separation
  • B03C1/02—Magnetic separation acting directly on the substance being separated
  • B03C1/28—Magnetic plugs and dipsticks
  • B03C1/284—Magnetic plugs and dipsticks with associated cleaning means, e.g. retractable non-magnetic sleeve
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
  • G01N35/0098—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor involving analyte bound to insoluble magnetic carrier, e.g. using magnetic separation

Definitions

• the invention relates to the processing of compositions containing magnetic particles, in which the particles are collected from a vessel containing the composition or are released as a composition in the vessel, and in which a magnetic rod is used to collect the particles to its tip or to release them from its tip.
• the invention relates specifically to the vessel and the rod used in the processing.
• the invention can be used for instance in various manufactaring, purification or analysis methods.
• Magnetic particles are used in various chemical processes as a solid phase, to whose surface a given component adheres. Owing to the particles, the available surface of the solid phase becomes as large as possible.
• the particle size is typically in the range from 0.05 to 10 ⁇ m.
• the particles can be moved by means of a magnetic field. Thus, for instance in a solution they may be transferred to the wall of a vessel . so that the remaining solution can be removed from the vessel by decanting or pipetting.
• the particles can also be separated from the solution by immersing a magnetic rod in the solution.
• Magnetic rods are also known, which comprise a vertically moving magnet within a cover. With the magnet in lower position, the particles can be collected on the rod surface, especially at its end. When the magnet is raised into upper position, the particles can be released from the rod accordingly.
• WO 94/18565 discloses rods used for collecting and transferring magnetic particles. They are preferably equipped with a cover with a sharp tip enclosing a movable magnet.
• the vessel used jointly with the rod may have a bottom matching the shape of the rod tip.
• the interstice between the rod and the vessel wall is made narrow on purpose, in order to make the liquid flow as rapidly as possible between the rod and the vessel wall when the rod is moved vertically. This enhances mixing and mass transfer.
• a vessel for a composition containing magnetic particles and a rod for collecting or transferring particles to be used together with the vessel have now been invented.
• the vessel is preferably symmetrical, such as circular, in cross-section, and the cross-sectional shape of the rod matches the cross-sectional shape of the vessel.
• the rod is equipped with a magnet, by means of which particles are collected on the rod surface, preferably at its tip portion.
• the magnet is preferably such a magnet whose action can be eliminated, so that the particles can be released from the rod surface.
• the magnet is preferably a permanent magnet, and most preferably a magnet that can be shifted between a collecting position and a releasing position within the rod.
• the direction of movement is especially the longitudinal direction of the rod.
• the collecting position of the magnet is preferably its lower position, from where it can be raised to the releasing position.
• the magnet preferably has a length that is significantly greater than its width. This allows particles to be efficiently collected on the rod tip. For the same reason, the upper end of the magnet preferably remains continuously above the composition surface while the particles are collected (cf. WO 96/12958). To this end, the length of the magnet can be clearly greater than the height of the liquid column to be treated.
• the ratio of its length to its width is preferably at least about 5: 1 and most preferably at least about 10: 1.
• the rod preferably slopes downwards at every point, ending in a sharp tip. In this manner, the rod, when lifted from the liquid, tends to retain as small an amount of liquid as possible (cf. WO 94/18565 and WO 94/18564).
• the use of a long magnet allows more efficient operation in small volumes. A long magnet is useful also in large volumes, because it enlarges the dynamic area at both ends.
• the tip preferably also has a tapered concave tip portion, so that particles are efficiently released from the rod tip into a small vessel of the same order of magnitude as the tip portion of the rod (cf. WO 96/12959).
• the height of the tip portion is relatively small compared to the diameter of the magnet.
• the ratio of the height of the tip portion to the diameter of the magnet is 1: 1 - 1:2, such as about 1:1.5.
• the flat shape of the tip also has the purpose of achieving a reliable operating volume that is as small as possible.
• Particles can be collected with a specific apparatus, in which the vessels can be placed and which comprises means for moving the rods (cf. WO 94/18565).
• a plate especially a matrix- shaped plate, which comprises several rows of vessels in succession.
• a commonly used plate is the one called micro-titration plate, comprising 8*12 vessels, or wells, at 9 mm intervals.
• a plate with corresponding outer dimensions and 16*24 wells is also used.
• the apparatus intended for the treatment of the plates may comprise a row of rods equal to the number of wells in one row (cf. WO 94/18565 and Thermo Labsystems KingfisherTM Magnetic Particle Processor).
• the apparatus also allows the operation of several, such as two, plates simultaneously, especially in parallel.
• the interstice between the vessel and the rod is large enough to prevent the formation of a liquid ring or a ring part rising along with the rod and thereby removing liquid from the vessel.
• the liquid flows down between the rod and the vessel under the force of gravity.
• Ascending water could flow over the edge of the vessel e.g. into an adjacent vessel or in the tip of a removed tip to the subsequent process step.
• a suitable interstice between the rod and the vessel can be at least about 1 mm, such as at least about 1.5 mm, and preferably at least about 2 mm. In common cases, an interstice above 3 mm does not gain any additional benefit in this respect.
• the vessel bottom comprises a positioning recess, into which the rod tip is fitted with the rod at a sufficient distance from the inner wall of the vessel at every point.
• the positioning recess serves to compensate for positioning errors caused by the horizontal movement of the rod and the vessel.
• the recess centre preferably comprises a horizontal area, whose width corresponds to the positioning margin.
• the recess shape is preferably identical to that of the tip portion of the rod, so that the interstice between the recess and the tip portion becomes as small as possible.
• the interstice is preferably 0.05- 0.3 mm at the most, such as 0.1-0.2 mm.
• the horizontal area typically has a width in the range 0.5-2 mm, such as about 1 mm.
• the rod is most preferably such that it is usable also in conventional vessels with a flat or concave bottom of various sizes.
• the apparatus in which the vessel is treated by means of the rod comprises a vertically elastic means, which yields as the rod is lowered against the vessel bottom.
• the elastic means such as spring means, may be provided in a base included in the apparatus for the vessel, in the rod or its actuating gear, or in a plate comprising several vessels.
• the invention is suitable for use especially during operations in very small volumes.
• the lower limit may be e.g. 10 ⁇ l or even 5 ⁇ l.
• the invention is suitable for use also when particles are collected from a relatively great volume, e.g. a bacterial culture, and are transferred into a volume that may be up to many times smaller.
• Figure 1 shows the steps of collecting magnetic particles with the rod from a small amount of liquid in the vessel according to one embodiment of the invention.
• Figure 2 shows the steps of releasing the magnetic particles adhered to the rod of figure 1 into a small liquid amount in the vessel of figure 1.
• Figure 3 shows an apparatus of the invention provided with spring means.
• the circular well 1 shown in figures 1 and 2 comprises, at its bottom centre, a bottom recess 2 with relatively steep edges. There is liquid in the well recess.
• a rod 3 which has a circular cross-section and a diameter considerably smaller than the diameter of the well, but yet greater than the diameter of the recess.
• the rod has an internal bore starting from the upper end, and an elongated permanent magnet 4 which can be moved within the bore. When the magnet is in the lower position witliin the rod, magnetic particles can be collected on the rod tip (figure 1).
• the tip portion 5 of the rod tapers in order to be accommodated in the bottom recess 2 of the well.
• Magnetic particles adhering to the rod 3 can be released into the liquid in the well 1 (figure 2).
• the rod is introduced into the well with the magnet 4 in lower position, then the magnet is removed, and thereafter the rod without the magnet, so that the particles remain in the liquid in the well.
• the particles are collected from the liquid onto the rod tip.
• the tip portion 5 of the rod 3 is concave and ends in a sharp tip.
• the recess wall has a matching convex shape, so that the interstice between the rod tip portion and the well is as small as possible.
• the liquid thus moistens the entire tip portion, where particles may be present as they are being brought into the well with the rod.
• the liquid remains solidly in the interstice with the rod fitted in position in the recess.
• the liquid plate surrounding the tip portion will efficiently sweep the particles along from the top to the bottom by hydrodynamic forces.
• the bottom of the well 1 has a shape such that a small liquid amount dosed into the well naturally finds its way into the bottom recess 2 as completely as possible.
• the free surface of the liquid will be at a rninimum, so that the liquid tends to remain here under the action of surface tension.
• this corner has been given a mildly curved shape.
• An appropriate radius of curvature of the corner is e.g. 0.5-2 mm, such as about 1 mm.
• the bottom of the well 1 is continuously sloping from the corners to the bottom recess 2. Thus the liquid will flow naturally into the bottom recess.
• the bottom of the bottom recess 2 in the well 1 comprises a central horizontal area 6.
• the width of the area is determined by the positioning tolerances, so that it is ensured that the tip of the rod 3 always hits this horizontal area. There will be positioning errors if the wells or the rods are moved horizontally.
• the width of the horizontal area is then (at least) twice the estimated positioning error.
• the appropriate width of the area is typically 0.5-2 mm, such as about 1 mm.
• the interstice between the tip portion 5 of the rod and the wall of the bottom recess is slightly larger at the bottom end than at the top end.
• the aim is to reduce the interstice to a rninimum. It is typically 0.1-0.2 mm.
• the ratio of the length to the diameter of the magnet 4 is about 13: 1. Owing to the long magnet, the particles are collected as completely as possible precisely to the tip area of the rod 3. For the same reason, the height of the tip portion is relatively small compared to the diameter of the magnet. Typically, the ratio of the height of the tip portion to the diameter of the magnet is 1: 1-1:2, such as about 1: 1.5.
• the dimensioning of a usable well 1 and rod 3 could be the following: inner diameter of the well 7 mm, outer diameter of the rod 4 mm, inner depth of the well (without the bottom recess 5) 10 mm, depth of the bottom recess and height of the rod tip portion 1.5 mm, width of the flat bottom 6 of the recess 1 mm, radius of curvature of the bottom corner of the wall about 1 mm, radius of curvature of the bottom recess wall about 5 mm, radius of concavity of the rod tip about 4 mm, height of the magnet 4 about 40 mm and diameter of the magnet about 3 mm.
• the bottom recess 2 and the rod tip portion ensure that the interstice between the wall of the well 1 and the rod 3 is large enough and that the rod can be inserted all the way to the recess bottom, despite positioning tolerances caused by the transverse motion.
• the rod 3 can also be used in a conventional well with a flat or concave bottom.
• the vertical movement also has specific tolerances, and as a result, the tip of the rod 3 does not necessarily always reach its lower position at the well bottom.
• the maximum error caused by this is about ⁇ 0.5 mm.
• the relative inclination of the rod and the well causes an additional error.
• the error caused by this may be typically about ⁇ 0.3 mm.
• the relative inclination of a plate comprising several wells and a matrix comprising several rods causes an additional error. However, this error is small compared to those mentioned above.
• the vessel and the rod can be made of suitable plastic, e.g. polypropylene.
• the apparatus may be provided with vertical spring means to compensate for vertical motion tolerances.
• the arrangement in figure 3 uses a plate 7, which comprises a plurality of rows of wells 1. Similarly, a number of rods equal to the number of wells in a row have been connected to an arm parallel to the row to form a jointly moved row of rods. Each rod 3 holds a magnet 4 fastened to the arm 8. At its upper end, the arm has a gripping means 9, with which the arm is vertically moved.
• the plate is placed on a base 10. The base yields in the vertical direction owing to vertical spring means 11. When the row of rods is introduced into the wells, it is driven against the bottom 6 of the bottom recesses 2 and even somewhat further. Then the springs will balance the distance between the tip and the bottom of each rod to a minimum (almost to zero in the practice).
• the fastening arm of the rods 4 can be provided with springs.
• each arm 8 may be provided with springs separately.
• the gripping means 9 is placed glidingly between an upper stop 12 and a lower stop 13 in the arm, and between the gripping means and the lower stop, there is a spring 14 which presses the gripping means upwards.
• the spring arrangement is especially useful when very small wells (e.g. 5 to 10 ⁇ l) are used. It is also particularly useful when large plates or plates comprising numerous wells are used.

Landscapes

• Physical Or Chemical Processes And Apparatus (AREA)
• Apparatus Associated With Microorganisms And Enzymes (AREA)
• Automatic Analysis And Handling Materials Therefor (AREA)
• Walking Sticks, Umbrellas, And Fans (AREA)
• Soft Magnetic Materials (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)
• Water Treatment By Electricity Or Magnetism (AREA)
• Manipulator (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Sampling And Sample Adjustment (AREA)

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• 2000
  • 2000-03-14 FI FI20000583A patent/FI20000583A0/fi unknown
• 2001
  • 2001-03-13 EP EP01919490A patent/EP1185372B1/de not_active Expired - Lifetime
  • 2001-03-13 AT AT02017578T patent/ATE304898T1/de active
  • 2001-03-13 EP EP02017578A patent/EP1266694B1/de not_active Expired - Lifetime
  • 2001-03-13 DE DE60113515T patent/DE60113515T2/de not_active Expired - Lifetime
  • 2001-03-13 AT AT01919490T patent/ATE340651T1/de active
  • 2001-03-13 JP JP2001566811A patent/JP3921633B2/ja not_active Expired - Lifetime
  • 2001-03-13 WO PCT/FI2001/000242 patent/WO2001068263A1/en active IP Right Grant
  • 2001-03-13 RU RU2001133727/03A patent/RU2269382C2/ru active
  • 2001-03-13 DE DE60123353T patent/DE60123353T2/de not_active Expired - Lifetime
  • 2001-03-14 US US09/808,232 patent/US6596162B2/en not_active Expired - Lifetime
  • 2001-11-14 NO NO20015562A patent/NO323760B1/no not_active IP Right Cessation
• 2004
  • 2004-04-15 RU RU2004111807/03A patent/RU2297285C2/ru active
  • 2004-12-15 JP JP2004363179A patent/JP2005103544A/ja active Pending

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